Getting too little sleep has long been thought to contribute to overeating (nearly 300 calories more). A new study evaluating the amount of sleep twins get suggests that more sleep may help you keep the weight off if you have a genetic tendency to gain weight.

Dr. Nathaniel Watson, from the University of Washington, led the sleep research of 1,088 pairs of identical and non-identical twins. The study, published in the American Academy of Sleep Medicine's Sleep journal found that those twins who slept longer at night had lower body mass index (BMI) than their siblings who slept less. Importantly, more sleep (nine or more hours) seems to reduce the genetic risk of having higher BMI, while sleeping too little (under seven hours) made the "fat gene" account for more of the BMI differences (for the twins sleeping nine+ hours, genetic factors account for only 32% of weight variations, compared to the 70% of BMI differences for the twins sleeping fewer than seven hours).

"The less sleep you get, the more your genes contribute to how much you weigh. The more sleep you get, the less your genes determine how much you weigh," says lead author Nathaniel Watson, a neurologist and co-director of the University of Washington Medicine Sleep Center in Seattle.

Our body mass index is influenced by both genetic and environmental (i.e., lifestyle) factors. This study suggests sleep is an antidote if you're predisposed to gaining weight. Basically, lose weight by sleeping more.